FileSizeViewHelper

FileSizeViewHelper.php

<?php
namespace Your\Package\ViewHelpers\Format;

/*                                                                                 *
 * This script belongs to the TYPO3 Flow package "Your.Package.                    *
 *                                                                                 *
 *                                                                                 */

use TYPO3\Flow\Annotations as Flow;
use TYPO3\Fluid\Core\ViewHelper\AbstractViewHelper;

/**
 * ViewHelper rendering the size of a file
 */
class FileSizeViewHelper extends AbstractViewHelper {

	/**
	 * @var array
	 */
	protected $units = array('B', 'KB', 'MB', 'GB', 'TB', 'EB', 'ZB', 'YB');

	/**
	 * Format the filesize
	 *
	 * @param mixed $size The file's size in bytes or an instance of \TYPO3\Flow\Resource\Resource. If NULL the child nodes are used as size
	 * @param integer $precision The optional number of decimal digits to round to
	 * @return string The filesize with SI unit appended
	 */
	public function render($size = NULL, $precision = 2) {
		if ($size === NULL) {
			$size = $this->renderChildren();
		}
		if ($size instanceof \TYPO3\Flow\Resource\Resource) {
			$size = @filesize('resource://' . $size->getResourcePointer()->getHash());
		}

		# determine the unit
		$unit = reset($this->units);
		while($size > 1024) {
			$size /= 1024;
			$unit = next($this->units);
		}

		return sprintf('%s %s', round($size, $precision), $unit);
	}

}

?>

Usage:

{someResource -> x:format.fileSize()}

or

{x:format.fileSize(size: someFileSize)}

FYI: Since Flow 2.1 this is shipped with Fluid and can be used like

{fileSize -> f:format.bytes()}

(see https://forge.typo3.org/issues/49128)